1. Field of Art
This invention relates to devices for measuring characteristics of continuously rolled strip products and more particularly to the apparatus to support the device in the desired measuring position in relation to the strip product.
2. Brief Description of the Prior Art
Many products and materials are produced or processed in a continuous strip form at one or more stages of production. Depending upon the product or material, it is desirable to monitor or measure certain characteristics of the product as it is being manufactured or processed. For example, in the manufacture of nearly all sheet products, whether it be metal, plastic, paper or wood veneer, thickness of the product is important, and it is advantageous to continuously measure or monitor the thickness in order that changes may be made in the processing of the product, if necessary, to keep the thickness of the product within some allowable tolerance range.
Other examples of measurable characteristics that are important in product manufacture are flatness in metal sheet manufacture, moisture content in sheet paper and textiles, and thickness of applied coatings, such as paint, on coiled sheet metal.
A well-known method for taking desired measurements on continuously processed products is to use transducers which typically comprise a radiation source, a pair of heads, one a sender and the other a receiver, and an indicating instrument to display or record the measurement being taken. Typically, one head of the transducer is positioned below the sheet or strip product being processed horizontally and the other head is supported above the product opposite and coaxially aligned with the lower head. Thus, a signal from the radiation source, such as an X-ray or beta ray, is transmitted from the sending head through the material to the receiver head and the receiver head is adapted to generate an electrical signal in response thereto that is recorded or displayed on an appropriate instrument in units relating to the material characteristic being measured.
A common support device for the transducer heads is a channel-shaped structure having an upper arm and a lower arm disposed above and below the strip material being processed transverse to the flow of the strip material. The upper and lower transducer heads are mounted in coaxial alignment on the channel arms with sufficient space between the opposing heads to allow passage of the strip material. The support system may include a drive means so that the channel-shaped structure or the heads may be moved transverse to the direction of movement of the strip material being produced or processed so that measurements may be made across the width of the strip or to move the transducer heads out of the way when convenient to gain unrestricted access to the strip.
One example of a channel-shaped transducer support system is disclosed in Ziffer U.S. Pat. No. 3,190,261. A system is described which employs two transducer units to monitor and control the thickness of a coating being applied to a continuously moving strip of paper. Opposing beta gauge sending and receiving heads are affixed to the ends of a channel-shaped structure which is slidably mounted to a lower carrying member which extends transversely across the process material strip. One transducer unit measures the thickness of the paper before the coating is applied and a second unit measures the thickness of the material after coating. By synchronizing the movement of the first and second transducer units in traverse across the width of material, comparative measurements may be made to reveal the thickness of the applied coating.
Mangan U.S. Pat. No. 3,474,668 discloses a similar support means of transducer heads in a method for controlling the profile of continuously rolled strip steel material.
Other patents which disclose channel-shaped transducer head support structures which are adapted for movement in a direction transverse to the flow of material being processed are Tompos et al U.S. Pat. No. 3,332,279 and Bossen U.S. Pat. No. 3,244,206.
Although the use of channel-shaped structures as a support means for transducer heads is adequate and satisfactory for the production and processing of many strip materials, space limitations sometime make it impractical or undesirable to use such a structure.
Accordingly, a support means for transducer heads employed in a system for measuring various characteristics of a continuously produced or processed strip material is desired which can be installed in a minimum amount of space and is adapted to permit one or both of the transducer heads to be moved from their measuring position to a position that conveniently allows access to the strip material.